When the story came out in the early 1970s, people didn’t see things that way. "As a society, we've decided that we can't turn people into human guinea pigs," says Klitzman.

By then, there were also second thoughts about a couple of social psychology’s greatest hits. Like the one where Yale psychologist Stanley Milgram got people to flip a switch they thought was going to kill someone.

In 1974, Congress passed the National Research Act, which led to the development of regulations for any research done by an institution receiving federal money.

The regulations boiled down to three things: First, minimize risks to study participants. Second, disclose those risks, so people know what they're getting into. And third, get an internal group at your institution has to sign off. That group is an Institutional Review Board, or IRB.

"IRBs are kind of overwhelmed," he says. "There’s a little bit of a tendnecy to say, 'Gosh, you know, there’s so much of this biomedical research where there’s, quote, real risks of people dying, or becoming disabled.' You know, 'How much attention should we be giving to this little stuff?'"

The "little stuff" being the kinds of emotional risks that got so much attention with Facebook's mood study.